Processing method utilizing display information and cell structure processed by the processing method

ABSTRACT

This is directed to a processing method for carrying a cell structure ( 1 ) with a catalytic component. Information about a mass of the cell structure ( 1 ) is displayed on the surface thereof prior to the initiation of a carrying process, and in the carrying process, the information is read and the cell structure ( 1 ) is carried with an appropriate amount of the catalytic component on the basis of the information. When cell structures are processed for carrying thereon a catalytic component, each cell structure can carry an appropriate amount of the catalytic component in accordance with the mass of the cell structure, even if there is a variation in the masses of the cell structures.

TECHNICAL FIELD

The present invention relates to a processing method for carrying anappropriate amount of a catalytic component on a cell structure. Thepresent invention can be applied to a catalyst carrier or a filter foruse in purifying or deodorizing an exhaust gas of an internal combustionengine, or to a catalyst carrier or a filter for use in a chemicalreaction instrument taking advantage of catalytic action such as areformer of a fuel cell or the like.

BACKGROUND ART

As an assembly employed for use in a catalytic converter, a filter, aheat exchanger or the like used for purifying the exhaust gas from aninternal combustion engine or used for a chemical reaction instrumenttaking advantage of catalytic action, there have been known articles inwhich cell structures are held by and housed in metallic containers(canning) by interposing a compressive material having a cushioningproperty between the cell structure and the metallic container (a canbody) and thereby giving a prescribed compressive contact stress to thecell structure through the compressive material.

For example, in the case where such an assembly is used as a catalyticconverter for use in purifying automobile exhaust gas, a ceramichoneycomb structure, a type of cell structure, in which noble metalssuch as platinum, palladium, rhodium, or the like are dispersed andcarried as catalytic components, is held by and housed in a metalliccontainer (a can body) through the intermediary of a ceramic mat or thelike, and is mounted in an exhaust system.

As in the above-described catalytic converter, in the case where acatalytic component is carried in the cell structure, an appropriateamount to be carried varies, depending on the masses of the cellstructures. Conventionally, the masses of the cell structures aremeasured beforehand and the cell structures are sorted into severalclasses based on mass, and the amount of the carried catalytic component(the mass of the catalytic component) is adjusted so as to become thefixed value by controlling the masses after the catalytic component hasbeen carried based on each class of the mass. However, since the massesof the cell structures have a certain variation even within the sameclass of the mass range, actually some variance exists in the carriedamount of the catalytic component if it is examined at the individualcell structures.

The present invention has been completed, in view of the above describedproblems in the prior art, and the object thereof is to provide aprocessing method for carrying a catalytic component on each cell withan appropriate amount thereof in accordance with the mass of the cellstructure, at the time when the processing for carrying a catalystcomponent on the cell structure is done, even if there is a variation inthe mass of the cell structure.

DISCLOSURE OF THE INVENTION

According to the present invention, there is provided a processingmethod (a first invention) for carrying a catalytic component on a cellstructure, characterized by displaying information about a mass of acell structure on the surface thereof prior to the initiation ofcarrying process, reading the information and carrying the cellstructure with an appropriate amount of a catalytic component on thebasis of the information in the carrying process.

Additionally, according to the present invention, there is provided aprocessing method (a second invention) for carrying a cell structurehaving been housed in and held by a metallic container via a compressivematerial having a cushioning property with a catalytic component,characterized by displaying information about a mass of a cell structureon the surface thereof prior to the initiation of carrying process,reading the information and carrying the cell structure with anappropriate amount of a catalytic component on the basis of theinformation in the carrying process.

Furthermore, according to the present invention, there is provided acell structure (a third invention) processed according to any of theabove described processing methods.

Yet furthermore, according to the present invention, there is provided acell structure (a fourth invention), having the above describedinformation displayed thereon, which is processed according to any ofthe above described processing methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) and (b) are illustrative views of a honeycomb structure usedas a cell structure in an embodiment, FIG. 1(a) being a plane view andFIG. 1(b) an oblique perspective view.

FIG. 2 is a diagram illustrating a method of marking barcodes by meansof a laser marker device.

BEST MODE FOR CARRYING OUT THE INVENTION

As described above, a first invention as a processing method forcarrying a catalytic component on a cell structure is characterized bydisplaying information about mass of a cell structure on the surfacethereof prior to the initiation of the carrying process, reading theinformation, and carrying the cell structure with an appropriate amountof the catalytic component on the basis of the information, in thecarrying process.

By controlling the carried amount of the catalytic component on thebasis of the information about the mass of the cell structure displayedon the surface of the cell structure, an appropriate amount of thecatalytic component may be carried in accordance with the actual mass ofthe cell structure, and consequently carrying an excess amount ofcatalytic component can be avoided and the catalytic component amountcan be saved.

In the first invention, characters and barcodes may be used for in themanner for displaying the information. Additionally, the information maybe displayed by ink coating, a laser, sand blast, chemical corrosion, orthe like. When the information is displayed by ink, it is preferable touse an ink jet method or a thermal transcription method.

As a cell structure, there is preferably used a honeycomb structurehaving a plurality of cell passages defined by a plurality of partitionwalls, the thickness of cell partition wall of 0.11 mm or less and theopening ratio of 85% or more. Furthermore, as the honeycomb structure,it is preferable that the structure has an outer wall forming an outerdiameter contour around the structure, with the thickness of the outerwall being at least 0.05 mm. Incidentally, the cell structures used inthe present invention may include a foamed structure, in addition to thehoneycomb structures as described above.

It is preferable that the cell structure is made of a ceramic materialor a compound comprising two or more ceramic materials selected from thegroup consisting of cordierite, alumina, mullite, lithium aluminumsilicate, aluminum titanate, titania, zirconia, silicon nitride,aluminum nitride, and silicon carbide. Additionally, there can besuitably used a cell structure which is made of one adsorptive materialselected from the group consisting of activated charcoal, silica gel,and zeolite.

Incidentally, the cell shape of a honeycomb structure produced byextrusion includes a trigon, a tetragon, a hexagon, a circle, or thelike; in general, there are frequently used honeycomb structures havingcells each shaped in a square, namely in a tetragon, but recently therehave been increasingly used the honeycomb structures having hexagonalcells.

In the case where a cell structure is used as a catalytic converter, itis necessary to carry the cell structure with a catalytic component, andthe cell structure is housed in and held by a metallic container usuallyafter the cell structure has been carried with the catalytic component;however, as in the following second invention, the cell structure may bemade to carry thereon the catalytic component after the cell structurehas been housed in and held by the metallic container.

The second invention is characterized by carrying a cell structurehaving been held by and housed in a metallic container through acompressive material having a cushioning property with a catalyticcomponent, in the processing method for carrying the cell structure withthe catalytic component, displaying information about the mass of thecell structure on the surface of the metallic container prior to theinitiation of the carrying process, reading the information and carryingthe cell structure with an appropriate amount of the catalytic componenton the basis of the information, in the carrying process.

In the other words, the second invention controls the carried amount ofthe catalytic component based on the information about the mass of thecell structure, similarly to the first invention; however, the catalyticcomponent is carried after the cell structure has been housed in andheld by the metallic container, and accordingly the information displayposition is located on the metallic container surface but not on thecell structure surface which is made hidden in the metallic container.The action effect attained in the second invention is similar to theeffect attained in the above described first invention.

Incidentally, in the first and second inventions, there can be used thedisplay manners and display measures similar to those in the abovedescribed first invention.

A third invention is the cell structure processed according to themethod related to the above described first or second invention, whichis made to carry an appropriate amount of a catalytic component asdescribed above, and accordingly can be suitably employed for use in thecatalytic converter for purifying the automobile exhaust gas or thelike. Additionally, a fourth invention is the cell structure beforeprocessing which is to be processed according to the method related tothe above described first invention and has the information displayedthereon; the information is displayed thereon beforehand through theabove described various manners and measures, and the processing methodof the first invention is realized on the basis of the information. Thesuitable structures, materials or the like for the cell structure are asdescribed above.

EXAMPLES

Further detailed description will be made below on the presentinvention, with reference to an example of the case in which a catalyticconverter is produced by use of a honeycomb structure 1 as shown in FIG.1(a) and (b) as the cell structure; however, the present invention isnot limited to these examples.

As for the methods of making the information such as characters andbarcodes be displayed on a honeycomb structure, the method based on anink jet printing device and the method based on a laser device arepreferable for the purpose of processing a large number of members,because these methods are fast and of the non-contact type printing.Particularly, a laser based method is more preferable than the ink jetmethod from the viewpoint of maintenance because it does not need anyink and does not require any pre-processing to be made beforehand.

The examination of the mass of a honeycomb structure is performed at theend of the production process of the honeycomb structure, and theinformation about the mass thereof examined and measured is made to bedirectly transmitted from the measurement instrument to a laser markerdevice. As shown in FIG. 2, a honeycomb structure 1 having left themeasurement instrument is then delivered to the laser marker device 3where marking of the barcodes is made on the outer surface of thehoneycomb structure 1 on the basis of the information about the masssimultaneously transmitted. A QR code is more preferable because it issmall in marking area and accordingly requires a short marking time, andis hardly affected by the outer surface curvature of the honeycombstructure.

An example of the laser marking conditions will be described below.Incidentally, a YAG pulsed laser device or a CO₂ (carbon dioxide) gaslaser device is suitable as a laser marker device.

-   -   Laser marker device:        -   A YAG laser marker device (manufactured by Miyachi Technos            Corp., lamp excitation type, ML-4141B)        -   Honeycomb structure:        -   A cordierite based honeycomb structure (partition wall: 2            mil; cell density: 900 cpsi; nominal outer diameter φ: 106            mm; length: 114 mm)    -   Marking conditions:        -   Current value: 17A; Q. SW frequency: 8 kHz; scan speed: 150            to 1000 mm/s    -   Barcode type:        -   CODE 39 or QR code; CODE 39 narrow width: 0.38 mm; QR code            cell size: 0.508 mm    -   Information carried by barcodes:        -   The mass value actually measured for a honeycomb structure

The ceramic honeycomb structure undergoes the barcode marking in theproduction process under such laser marking conditions as describedabove, and is then delivered to the process for carrying the catalyticcomponent. Immediately before the catalytic component is carried, thebarcodes marked on the ceramic honeycomb structure and the informationabout the mass thus marked is read by a barcode reader, and istransmitted to a device for carrying a catalyst. The honeycomb structuredelivered into the device for carrying a catalyst is carried with thecatalytic component after the conditions have been adjusted on the basisof the specific information about the mass.

The honeycomb structure carried with the catalytic component isdelivered to a catalyst baking process where it is processed at atemperature of about 600° C. or higher. It is desirable to use anheat-resistant ink when the ink jet method is used, because there is anapprehension that the information displayed on the honeycomb structurewill become unreadable or be burned owing to the discoloration of thehoneycomb structure in the catalyst carrying process or the catalystbaking process.

In general, owing to masking, the catalytic component is not carried onthe outer surface of the honeycomb structure, and accordingly the markedinscription such as the barcodes or the like does not come to be buriedby the catalytic component, but some discoloration cannot be avoided;accordingly, it is necessary to specify the marking conditions for thebarcodes or the like so that the marked inscription may be read. In thecase of the laser marking, the member surface is decomposed and removedin a very shallow region, so that the honeycomb structure carried withthe catalytic component by passing through the process for carrying itwith the catalytic component is then delivered to the canning process.

The character information can be printed similarly to the barcodes bythe ink jet method or the laser marking method. In this case, theprinted character information is recorded by a CCD camera and recognizedby a pattern matching method. This method is a method in which thecharacters are registered beforehand, and the patterns closest to theregistered characters are selected from the dark and light informationof the recorded characters. The present inventors made the numericalcharacter information about the mass displayed by the above lasermarking method be read on a F350 image recognition device manufacturedby Omron Corp., and confirmed that the information was able to betransmitted without fail.

The reading principle of a barcode reader is that a laser light beam isirradiated on a barcode label and the diffuse reflection light therefromis received by the light receiver in the barcode reader. In the diffusereflection light, weak and strong intensities are generated by thereflectivity differences between the spaces and the bars, and suchintensities are converted to the ON/OFF digital signals so that thespaces and bars are discriminated and read. Accordingly, in the casewhere even with the barcodes the weak and strong intensity differences(PCS) come to be small in the diffuse reflection light, reading on abarcode reader becomes difficult, and hence the above described imagerecognition processing method becomes effective.

Additionally, a method is possible in which the honeycomb structure isheld in a metallic container before the catalytic component is carried,and then the honeycomb structure is made to carry the catalyticcomponent. According to this method, it is possible to avoid the troublethat the honeycomb structure is chipped or broken during the process forcarrying the catalytic component. In this case, the masses of thecompressive material and the metallic container are added to the mass ofthe honeycomb structure, and hence the total mass as an assembly becomesvery heavier as compared to that of the honeycomb structure; thus, forthe purpose of controlling the carried amount of the catalyst, thecontrolling becomes very difficult because the mass distributions bothof the compressive material and of the metallic containers are added inaddition to the mass distribution of the honeycomb structures.Accordingly, the control of the carried amount of the catalyticcomponent becomes easy by adopting a way in which the information aboutthe mass of the honeycomb structure is displayed on the outer surface ofthe metallic container, and the catalytic component is made to becarried on the basis of such information about the mass.

Industrial Applicability

As described above, according to the present invention, when a processis performed in which the cell structures are made to carry thecatalytic component, the appropriate amount of the catalytic componentin conformity with the mass of each cell structure can be carried evenif the masses of the cell structures are distributed.

1. A processing method in which a cell structure is carried with a catalytic component, characterized by comprising: a step of measuring a mass of the cell structure; a step of displaying information about the measured mass of the cell structure on the surface of said cell structure; a step of reading said information before prior to carrying of a catalyst; a step of determining the catalytic component amount to be carryied on the basis of said read information; and a step of carrying said cell structure with the determined amount of the catalytic component.
 2. The processing method according to claim 1, in which the cell structure is a cell structure housed in and held by a metallic container through a compressive material having a cushioning property.
 3. The processing method according to claim 1, in which characters are used for making said information be displayed on the cell structure.
 4. The processing method according to claim 1, in which barcodes are used for making said information be displayed on the cell structure.
 5. The processing method according to claim 3, in which an ink is used for making said information be displayed on the cell structure.
 6. The processing method according claim 5, in which the method using an ink for making said information be displayed on the cell structure is a method using ink jet or a method using thermal transcription.
 7. The processing method according to claim 3, in which a laser is used for making said information be displayed on the cell structure.
 8. The processing method according to claim 3, in which sand blast is used for making said information be displayed on the cell structure.
 9. The processing method according to claim 3, in which a chemical corrosion is used for making said information be displayed on the cell structure. 